How common is this across all vaccines in general (irrespective of how low the probabilities are in each case.)
And this isn't the first time a Polio vaccine has caused the disease [0]:
> In April 1955 more than 200,000 children in five Western and
> mid-Western USA states received a polio vaccine in which the
> process of inactivating the live virus proved to be defective.
> Within days there were reports of paralysis and within a month
> the first mass vaccination programme against polio had to be
> abandoned. Subsequent investigations revealed that the vaccine,
> manufactured by the California-based family firm of Cutter
> Laboratories, had caused 40,000 cases of polio, leaving 200
> children with varying degrees of paralysis and killing 10.
All existing vaccines have risk, however they're at least a factor off 100 safer. I find if you explain this, and why they're still a good choice people respond well. Especially if you give the history of people / scientists working on them. There was a study posted on HN a while back that showed mothers who were given an explanation months before birth had a higher vaccination uptake rate.
mRNA vaccines are qualitatively different, though, not just slightly further on a sliding scale. The only risks AFAIK are from the delivery mechanism and the immune response; the payload itself is, well, mRNA molecules, which can't produce pathogens at all.
While you correctly identify the cause, the rates of myocarditis and pericarditis younger people receiving the vaccine are far higher than with other vaccines we give. See https://bmjopen.bmj.com/content/12/5/e059223 for verification.
As a result some countries, such as Sweden, have opted to NOT offer COVID vaccines to children under 12. https://www.euronews.com/next/2022/02/25/covid-vaccine-for-c...
The fact that the USA shut down the discussion before it even happened is a problem.
Which is a risk. The mRNA vaccines AFAICT are somewhere around a factor 100x safer than covid-19 for the general population. I hope research gets published that get that number more accurate.
Also, it seems risks like myocarditis stem from the lack of common best practices around the delivery mechanism like dosing and hopefully could be reduced.
https://www.verywellhealth.com/what-is-a-live-virus-vaccine-... is a recent article with a partial list of common vaccines that are live. They tend to be more effective than alternative vaccines. And, unless you are immunocompromised, they are very unlikely to make you sick.
What makes the polio vaccine more complicated is that it is given orally, multiplies, passes through your body, and comes out in your feces. Which gives it a route by which it can infect people other than the person who received the vaccine. The same does not happen with injected live vaccines.
There is an inactivated polio vaccine that is given with a needle. That is used by the USA and most advanced countries. But it is more expensive, is harder to deliver (you need multiple shots on a schedule), and is less effective. It does protect the recipient against becoming paralyzed, but does not stop you from getting a mild stomach infection and passing it on in your feces where you can spread it to others. Therefore only the oral vaccination can halt an active community outbreak.
However the fact that the oral vaccine can also START a community outbreak means that we have to be careful where we use it.
You're not going to see that with mRNA vaccines, you're not going to see that with the adenovirus-vectored vaccines. You're not going to see that with inactivated virus vaccines (like most influenza[*] or CoronaVac or the Sinopharm COVID vaccines).
Live attenuated virus vaccines are one of the oldest vaccine methods and have been around since the 19th century. They're created by culturing the virus serially in artificial media and isolating a strain which is less virulent. Very brute force laboratory methods that only require the ability to culture the virus and an animal model of virulence with decent correspondence to human virulence.
One thing to remember is that we're dealing with a medical triage situation and its better to cause a very small amount of disease in order to eradicate most of it. People get hung up on the fact that medical science is a human activity that doesn't have perfectly flawless outcomes like in Star Trek, while the natural diseases are orders of magnitude worse.
[*] Except the Flumist nasal spray is live attenuated. Still with influenza that isn't likely a big deal. I would be willing to wager a bit that this technique is still being used there because the influenza virus is very good at getting past the nasal mucosa and we don't know how to engineer particles that do that very well (still no nasal COVID vaccine).
For example, subunit vaccines like the whooping cough vaccine use a portion/fragment of the infectious agent, which means it is literally impossible for such a vaccine to cause the illness it is supposed to work on since there is none of that agent in the vaccine in the first place.
Attenuated vaccines, such as some polio vaccines and the MMR vaccine, include a weakened version of the infectious agent. These types of vaccines can result in a full-blown infection, especially in immunocompromised people.
So in short, the risk of a full-blown infection from a vaccine is going to depend on the type of vaccine, and I suspect there's variation within each type as well.
There's more info on the various types of vaccines at https://www.hhs.gov/immunization/basics/types/index.html
>If a layman said this I would have dismissed them as a conspiracy nut
Should make you think about how most of us approach the problem, right? How often are we told a truth and despite not knowing anything about the topic we dismiss it as nonsense? If you're an expert in some niche field you'll know it happens all the time.
You have to activate the immune system somehow. Sometimes presenting deactivated viruses or parts of viruses - viral capsids or nucleic acids - is not enough. Sometimes you can't find a good adjuvant.
For anyone who wants to look up more, the word "attenuated" is used to describe this.
> This is not the case with most modern vaccines
It's actually really common, just not with flu shots: https://www.hhs.gov/immunization/basics/types/index.html
My recollection:
There are two types of polio vaccine, one made from live germs and one made from killed germs. You cannot get polio from the killed polio version.
IIRC, polio vaccines are the primary cause of polio today.